Case in Sql group by query - sql

Question

I am working on a project in which I want to use Case to calculate price of product under specific Reference Number in SQL server. Below is my Sql query
SELECT
product AS Products,
refNum AS Refrence,
COUNT(id) AS Count
FROM ProductPriceList
GROUP BY
refNum, product
By Executing Above query I get:
Product Reference Count
Product1 Ref08 24
Product2 Ref08 7
Product3 Ref07 32
Product2 Ref12 1
Product3 Ref12 18
Product1 Ref07 76
Product1 Null 56
Can anyone guide me how to use Case statement in Sql query with group by statement to show price Below is the case:
if count < 10 then price 1
if count > 10 and < 100 then price 2
if count > 100 then price 3
I don't want to add a new table in my database. I hope you can understand my query.
Thanks in advance.

Answer 1

I think a basic CASE expression can handle your requirement:
SELECT
product AS Products,
refNum AS Refrence,
CASE WHEN COUNT(*) < 10 THEN 1
WHEN COUNT(*) >= 10 AND COUNT(*) < 100 THEN 2
ELSE 3 END AS price
FROM ProductPriceList
GROUP BY
product, refNum;
Not much to explain here, except that the 2 price case uses a bound which includes the count of 10 (since the 1 price case excludes it).

Answer 2

Here's alternative (doesn't differ much from exisiting one though):
You can use your query in subquery and use case outside:
select product,
--to get NULL values back
case Reference when 'RefNull' then NULL else Reference end [Reference],
case when [Count] < 10 then 1
when [Count] between 10 and 100 then 2
else 3 end [price]
from (
SELECT product AS Products,
--to allow also null values to be grouped
coalesce(refNum, 'RefNull') AS Refrence,
COUNT(id) AS Count
FROM ProductPriceList
GROUP BY coalesce(refNum, 'RefNull'), product
) [a]

Answer 3

Dataset:
Create Table ProductPriceList
(
Product varchar(10)
,RefNum CHAR(5)
,Records Int
);
Insert into ProductPriceList
Values
('Product1','Ref08',24)
,('Product2','Ref08',7)
,('Product3','Ref07',32)
,('Product2','Ref12',1)
,('Product3','Ref12',18)
,('Product1','Ref07',76)
,('Product1', NULL, 56);
With RCTE AS
(
Select Product
,RefNum
,Records
,1 RowNo
From ProductPriceList PPL
Union All
Select Product
,RefNum
,Records
,RowNo + 1
From RCTE R
Where RowNo + 1 < Records
)
Insert Into ProductPriceList (Product, RefNum, Records)
Select Product, RefNum, Records
From RCTE
where Records > 1
Query to fetch desired result:
Select Product
,RefNum
,Case When Count(*) < 10 Then 1
When Count(*) Between 10 and 99 then 2
Else 3 End Price
From ProductPriceList
Group By Product, RefNum
SQL Fiddle